CN106164017B

CN106164017B - Composite sintered body

Info

Publication number: CN106164017B
Application number: CN201580017546.0A
Authority: CN
Inventors: 佐藤武; 角谷均
Original assignee: Sumitomo Electric Industries Ltd
Current assignee: Sumitomo Electric Industries Ltd
Priority date: 2014-04-30
Filing date: 2015-03-16
Publication date: 2020-09-01
Anticipated expiration: 2035-03-16
Also published as: JP2015209369A; WO2015166731A1; US9950960B2; CN106164017A; EP3138828A1; EP3138828A4; EP3138828B1; JP6390152B2; US20170008807A1

Abstract

The composite sintered body includes a first phase and a second phase. The first phase is a diamond phase, the second phase is a phase formed using at least one element or compound or both, and the second phase applies strain to the first phase. The content of the second phase is more than 0ppm and not more than 1000 ppm. Thus, a diamond-containing composite sintered body having high wear resistance, high partial wear resistance and high chipping resistance is provided.

Description

Composite sintered body

Technical Field

The present invention relates to a diamond-containing composite sintered body.

Background

Diamond is a substance having the highest hardness among substances present on the earth, and therefore, a sintered body containing diamond has been used as a material for wear resistant tools, cutting tools, and the like.

Japanese patent laid-open No.2003-292397 (patent document 1) discloses a diamond polycrystal which is a polycrystal composed of diamond obtained by converting and sintering a carbon substance of a graphite-type layered structure at high temperature and high pressure without adding a sintering aid and a catalyst, wherein the diamond has an average particle diameter of 100nm or less and a purity of 99% or more. Japanese patent laid-open No.2003-292397 (patent document 1) also discloses a method of manufacturing diamond polycrystal by direct conversion without adding a sintering aid and a catalyst by placing a non-diamond carbon substance in a pressure unit including an indirect heating means and heating and pressurizing.

International publication No.2009/099130 (patent document 2) discloses a diamond polycrystal obtained by converting and sintering non-diamond carbon under ultrahigh temperature and ultrahigh pressure without adding a sintering aid and a catalyst, in which sintered diamond particles forming the diamond polycrystal have an average particle diameter of more than 50nm and less than 2500nm and a purity of 99% or more, and the particle diameter of D90 of diamond is (average particle diameter + average particle diameter × 0.9) or less.

Japanese patent laying-open No.9-142933 (patent document 3) discloses a diamond sintered body containing 0.1 to 30 vol% of a substance composed of an oxide and/or oxycarbide and/or carbide of a rare earth element, and the balance being diamond.

Japanese patent laid-open No.2005-239472 (patent document 4) discloses a diamond sintered body having high strength and high wear resistance, which contains sintered diamond particles having an average particle diameter of 2 μm or less, and the balance being a binder phase, wherein the content ratio of the sintered diamond particles in the diamond sintered body is 80 vol% or more and 98 vol% or less, and the binder phase contains cobalt and at least one or more elements selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium, and molybdenum; the content ratio of cobalt in the binder phase is 50 mass% or more and less than 99.5 mass%; the content ratio of the at least one or more elements in the binder phase is 0.5 mass% or more and less than 50 mass%; and at least one or more elements selected from the group consisting of titanium, zirconium, hafnium, vanadium, niobium, tantalum, chromium and molybdenum are present in the form of carbide particles having an average particle diameter of 0.8 μm or less, the structure of the carbide particles being discontinuous, and adjacent diamond particles being bonded to each other.

Reference list

Patent document

Patent document 1: japanese patent laid-open No.2003-292397

Patent document 2: international publication No.2009/099130

Patent document 3: japanese patent laid-open No.9-142933

Patent document 4: japanese patent laid-open No.2005-239472

Disclosure of Invention

Technical problem

When the diamond polycrystals disclosed in japanese patent laid-open No.2003-292397 (patent document 1) and international patent laid-open No.2009/099130 (patent document 2) are applied to a wire-drawing die as a wear-resistant tool, the pull-out resistance at the time of wire drawing increases, and the wire diameter after wire drawing decreases and wire breakage may be caused to occur frequently due to local wear in the die. When the diamond polycrystal is applied to a water jet (water jet) as a cutting tool, there is a possibility that the service life of the tool may be shortened due to severe abrasion of the nozzle hole portion.

When the diamond sintered bodies disclosed in japanese patent laid-open No.9-142933 (patent document 3) and japanese patent laid-open No.2005-239472 (patent document 4) are applied to a wire drawing die as a wear-resistant tool, the friction coefficient is increased due to metal carbides and metals in the sintered bodies, and thus the wire drawing resistance may be increased, the wire diameter after wire drawing may be reduced, and wire breakage may frequently occur. When the diamond sintered body is applied to a rotary tool, the friction coefficient is increased due to metal carbide and metal in the sintered body, so that cutting resistance may be increased, and tool breakage may occur. When the diamond sintered body is applied to a cutting tool, the friction coefficient increases due to metal carbide and metal in the sintered body, so cutting resistance increases, and excessive vibration occurs and a smooth cutting surface may not be obtained. When the diamond sintered body is applied to an excavating bit, internal destruction occurs due to linear expansion of the metal in the sintered body, thereby possibly shortening the tool life.

The present invention has been made to solve the above problems, and an object thereof is to provide a diamond-containing composite sintered body having high wear resistance, high partial wear resistance, and high chipping resistance.

[ means for solving the problems ]

The composite sintered body of the present invention is a composite sintered body comprising a first phase and a second phase, wherein the first phase is a diamond phase, the second phase is a phase formed of one or more elements or compounds or both, and the second phase applies a strain to the first phase, and the content of the second phase is greater than 0ppm and 1000ppm or less.

Effects of the invention

Since the composite sintered body of the present invention has the above-described constitution, the wear resistance, the partial wear resistance and the chipping resistance are improved.

Detailed Description

Description of embodiments of the invention

First, the outline of the embodiment of the present invention (hereinafter also referred to as "the present embodiment") is described below by listing it as (1) to (5) below.

(1) A composite sintered body according to an embodiment of the present invention is a composite sintered body including a first phase and a second phase, wherein the first phase is a diamond phase, the second phase is a phase formed of one or more elements or compounds or both, and the second phase applies strain to the first phase, and the content of the second phase is greater than 0ppm and 1000ppm or less.

Since the composite sintered body according to the embodiment of the present invention has the above-described configuration, wear resistance, partial wear resistance, and chipping resistance are improved, and occurrence of cracks can be suppressed.

(2) In the composite sintered body according to the present embodiment, the linear expansion coefficient of the second phase is preferably higher than that of the first phase. Thereby, the wear resistance, partial wear resistance and chipping resistance of the composite sintered body are further improved.

(3) In the composite sintered body according to the present embodiment, the average particle diameter of the particles forming the first phase is preferably 1000nm or less. Thereby, the wear resistance, partial wear resistance and chipping resistance of the composite sintered body are further improved.

(4) In the composite sintered body according to the present embodiment, the average particle diameter of the particles forming the second phase is preferably 500nm or less. This further improves the wear resistance, local wear resistance, and chipping resistance of the composite sintered body, and can suppress the occurrence of cracks.

(5) In the composite sintered body according to the present embodiment, the knoop hardness of the composite sintered body is preferably 60GPa or more in order to improve wear resistance.

[ detailed description of embodiments of the invention ]

Although the composite sintered body according to the present embodiment will be described in more detail below, the present embodiment is not limited thereto.

(composite sintered body)

The composite sintered body according to the present embodiment is a composite sintered body including a first phase and a second phase. The first phase is a diamond phase, the second phase is a phase formed from one or more elements or compounds, or both, and the second phase imparts strain to the first phase. The content of the second phase is more than 0ppm and 1000ppm or less.

The above composite sintered body may contain other components such as a sintering aid and a catalyst in addition to the first phase and the second phase.

In the observation of a cross section (an arbitrarily specified cross section, the same applies hereinafter) of the composite sintered body by SEM (scanning electron microscope) or TEM (transmission electron microscope), the presence of a diamond phase was recognized as a bright field, and the presence thereof was confirmed by composition analysis and crystal structure analysis.

The average particle diameter of the particles forming the diamond phase is preferably 1000nm or less, and more preferably 500nm or less, from the viewpoint of improving the local wear resistance and chipping resistance of the composite sintered body. Further, the average particle diameter of the particles forming the diamond phase is 50nm or more, and preferably 200nm or more. Here, the average particle diameter of the particles forming the diamond phase is obtained by: when a cross section of the composite sintered body is observed by SEM or TEM, a photograph is taken under conditions that enable discrimination between the diamond phase, the second phase, and the grain boundary therebetween, followed by image processing (for example, binarization) to calculate an average value of the areas of the respective particles forming the diamond phase, and then the diameter of a circle having the same area as the area is calculated.

In the composite sintered body according to the present embodiment, the second phase is a phase formed of one or more elements or compounds or both, and the second phase applies strain to the first phase. In use of the composite sintered body, the above-mentioned second phase undergoes linear expansion due to frictional heat to apply a compressive stress to the diamond matrix, thereby increasing the hardness of the matrix and reducing wear.

The linear expansion coefficient of the second phase is preferably higher than that of the first phase. Thereby, the effects of increasing the hardness and reducing the wear can be further enhanced. The measurement of the linear expansion coefficient of the second phase was performed by using the following method. First, the composition and crystal structure of the second phase of the composite sintered body were determined by using SEM and TEM methods. Next, a raw material having this composition is separately prepared, and a sintered body including only the second phase is produced by using a desired method. Finally, the obtained sintered body was measured by using the JISR1618 method, thereby obtaining the linear expansion coefficient.

Examples of the above second phase may include SiC, Al, Ti, V, and the like.

In order to prevent cracks and fractures from occurring in the composite sintered body due to excessive expansion of the first phase or the second phase, the content of the second phase in the composite sintered body is 1000ppm or less, and preferably 700ppm or less. In order to reduce friction and wear in the second phase, the content of the second phase in the composite sintered body is more preferably 500ppm or less. Further, in order to apply an appropriate compressive stress to the diamond phase, the content of the second phase is more than 0ppm, preferably 100ppm or more and more preferably 400ppm or more. In the observation of the cross section of the composite sintered body by SEM or TEM, the second phase present in the composite sintered body was recognized as a dark field, and its presence was confirmed by composition analysis and X-ray diffraction.

In order to suppress the occurrence of local cracks in the composite sintered body due to excessive expansion of the first phase or the second phase, the average particle diameter of the particles forming the second phase is preferably 500nm or less. Further, in order to reduce local abrasion in the second phase, the average particle diameter of the particles forming the second phase is preferably 100nm or less. Further, from the viewpoint of improving the structural hardness, the average particle diameter of the particles forming the second phase is 10nm or more, and preferably 50nm or more. Here, the average particle diameter of the particles forming the second phase is obtained by: when a cross section of the composite sintered body is observed by SEM or TEM, a photograph is taken under conditions that enable discrimination between the diamond phase, the second phase, and the grain boundary therebetween, followed by image processing (for example, binarization) to calculate an average value of the areas of the respective particles forming the second phase, and then the diameter of a circle having the same area as the area is calculated.

In order to improve the wear resistance of the composite sintered body, the knoop hardness of the composite sintered body according to the present embodiment is preferably 60GPa or more, and more preferably 80GPa or more. Here, the knoop hardness was measured by using a knoop indenter under a measurement load of 9.8N (1.0 kgf).

[ method of producing composite sintered body ]

The method for producing the composite sintered body according to the present embodiment is not particularly limited. However, in order to manufacture a composite sintered body having high wear resistance, high partial wear resistance, and high chipping resistance in an efficient manner and at low cost, the manufacturing method of the composite sintered body according to the present embodiment preferably includes the steps of:

(a) a raw material preparation step in which a mixture of the raw material non-diamond carbon, the raw material diamond, and the second phase-forming substance, or a mixture of the raw material non-diamond carbon and the second phase-forming substance is prepared.

(b) A composite sintered body forming step of forming a composite sintered body by sintering the aforementioned raw materials under conditions of temperature and pressure at which a diamond phase is formed.

The raw material non-diamond carbon and the raw material diamond prepared in the raw material preparation step are preferably powders in order to form a homogeneous composite sintered body. Further, in order to form a high-quality composite sintered body, the raw material non-diamond carbon is preferably graphite or amorphous carbon.

In the composite sintered body forming step, the sintering conditions are not particularly limited as long as the sintering conditions are temperature and pressure conditions capable of forming a diamond phase. However, in order to efficiently form the diamond phase, the conditions of temperature of 1800 ℃ or more and pressure of 8GPa to 16GPa are preferable, and the conditions of temperature of 2000 ℃ to 2200 ℃ or less and pressure of 11GPa to 14GPa are more preferable. The high temperature and high pressure generating device for generating such high temperature and high pressure is not particularly limited, and examples of the high temperature and high pressure generating device include a band type device, a cube (cubic) type device, a division ball type device, and the like.

Examples

(example 1)

1. Preparation of the raw materials

A mixed powder obtained by adding 400ppm of silicon carbide to graphite powder was prepared as a raw material.

2. Formation of composite sintered body

The mixed powder was sintered for 100 minutes under sintering conditions of a temperature of 2300 ℃ and a pressure of 13GPa using a high-temperature high-pressure generator, thereby obtaining a composite sintered body.

3. Evaluation of Properties of composite sintered body

The diamond phase and the second phase in the composite sintered body were identified and confirmed by SEM observation and X-ray diffraction of one cross section of the composite sintered body, the content of the second phase was calculated from the foregoing SEM observation, the content of the second phase was thus obtained as 300ppm, and the average particle diameter of the particles forming the diamond phase was calculated from the foregoing SEM observation, then, the average particle diameter of the particles forming the diamond phase was 300nm, the average particle diameter of the particles forming the second phase was calculated from the foregoing SEM observation, the average particle diameter of the particles forming the second phase was thus obtained as 60nm, the Knoop hardness of the composite sintered body was measured under a load of 9.8N using a Knoop indenter, the Knoop hardness of the composite sintered body was thus obtained as 75GPa, and further, the linear expansion coefficient of the diamond phase was 1.1 × 10.10^-6K, and the linear expansion coefficient of the silicon carbide phase is 6.6 × 10^-6/K。

Further, a wire drawing die having an opening size of 20 μm was manufactured using this composite sintered body, and SUS (stainless steel) was drawn at a wire drawing rate of 1000 m/min. The frequency of filament breakage until the opening size of the die was enlarged to 20.5 μm was significantly reduced to one fifth of that in the conventional technique.

Further, the composite sintered body was brazed to a superhard base metal to fabricate a cutting tool having a tip angle of 80 ° and a tip radius of curvature (R) of 80nm, and a nickel plate having a thickness of 20 μm was plated on a 30mm thick copper plate to obtain a nickel-plated metal plate on which grooves having a depth of 5 μm were formed at a pitch of 10 μm. When the wear of the tip of the cutting tool reached 1 μm, the defect state (cracks and chipping) of the tip portion was evaluated by the chipping amount. This results in a significant reduction in the amount of chipping to half that in the conventional technique.

It should be understood that the embodiments and examples disclosed herein are illustrative and are not intended to be limiting in any way. The scope of the invention is indicated by the appended claims rather than by the foregoing description, and is intended to include any modifications within the scope and meaning equivalent to the claims.

Claims

1. A composite sintered body comprising a first phase and a second phase,

the first phase is a diamond phase and,

the second phase is a phase formed of one or more elements or compounds, or both, and the second phase applies strain to the first phase,

the content of the second phase is more than 0ppm and not more than 1000ppm,

the second phase includes SiC.

2. The composite sintered body according to claim 1,

the value of the linear expansion coefficient of the second phase is greater than the value of the linear expansion coefficient of the first phase.

3. The composite sintered body according to claim 1 or 2,

the particles forming the first phase have an average particle diameter of 1000nm or less.

4. The composite sintered body according to claim 1 or 2,

the average particle diameter of the particles forming the second phase is 500nm or less.

5. The composite sintered body according to claim 1 or 2,

the Knoop hardness of the composite sintered body is 60GPa or more.